Poison Ivy

Scientific Name(s): Toxicodendron diversilobum (Torr. & A. Gray) Greene, Toxicodendron pubescens Mill., Toxicodendron radicans (L.) Kuntze, Toxicodendron rydbergii (Small ex Rydb.) Greene, Toxicodendron succedaneum (L.) Kuntze, Toxicodendron vernicifluum (Stokes) F.A. Barkley, Toxicodendron vernix (L.) Kuntze
Common Name(s): Chinese lacquer, Markweed, Poison dogwood, Poison elder, Poison ivy, Poison oak, Poison sumac

Medically reviewed by Drugs.com. Last updated on Oct 11, 2023.

Clinical Overview

Use

Quality clinical trials are lacking to support therapeutic applications.

Dosing

Poison ivy preparations should not be ingested due to potential for allergy and toxicity. Desensitization is not generally successful.

Contraindications

Not considered safe for use.

Pregnancy/Lactation

Avoid use. Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions

None well documented.

Adverse Reactions

Contact dermatitis, including black-spot poison ivy dermatitis, is well recognized.

Toxicology

Clinical information is limited.

Botany

"Poison ivy" or "poison oak" refers to several members of the Toxicodendron genus (formerly Rhus), which grow throughout the United States. Identification of the exact species has traditionally relied on the adage "leaves of 3, let it be;" however, poison oak can have 3 to 5 leaflets and nonpoisonous sumac can have up to 13 leaflets. The nontoxic Virginia creeper (Parthenocissus quinquefolia) can also be mistaken for poison ivy.Gladman 2006, Parkinson 2002, USDA 2015

Images for identification are available on the US Department of Agriculture’s online PLANTS Database.USDA 2015 Generally, all species have U- or V-shaped leaf scars (where the leaf breaks from the stem), and flowers and fruits arise in the axillary position (the angle between the leaf and the branch). A black deposit is often present when Toxicodendron has been injured. Following trauma, the toxic oleoresin exudes, darkens with exposure to air, and hardens, which may assist in identification.Gladman 2006 Synonyms of T. pubescens include Rhus acutiloba, Rhus toxicarium, Rhus toxicodendron, Toxicodendron quercifolium, and Toxicodendron toxicarium.

Chemistry

An oily phenolic resin, termed "lobinol" by James B. McNair of the University of Chicago in the 1920s,(McNair 1921) is present in all poisonous Toxicodendron species and contains urushiol, a complex active principle derived from the Japanese term "sap." Urushiol is a mixture of antigenic catechols closely related to 3-n-pentadecylcatechol (3- PDC, hydrourushiol), varying in degree of saturation and length of side chain,(Duke 1992, Gladman 2006) and carried by resin canals in the bark, stem, leaflets, and certain flower parts. The relative percentages of 3-PDC and related catechols vary among the species and may be related to environmental conditions. The danger of toxicity is greatest in spring and summer when the sap is abundant, the urushiol content is high, and the plant is easily bruised.(Gladman 2006) Other chemical compounds in poison ivy include fisetin, gallotannic acid, kaempferol, myricetin, quercetin, rhamnose, and tannins.(Duke 1992) Additionally, heneicosandicarbonic, myristic, and palmitic acids have been identified in the fruit, and linoleic and oleic acids in the seeds.(Duke 1992)

The chemical composition of T. vernicifluum, and the lacquer sap/wax obtained from this species, is also under investigation, with polysaccharides, phenolic, and sesquiterpenoid compounds of interest.(Bai 2013, Chen 2014, He 2013, Jin 2015, Song 2010) A review of the chemical constituents of T. vernicifluum has been published.(Li 2021)

Uses and Pharmacology

A review of the potential pharmacological applications, based primarily on in vitro studies, has been published. Anti-inflammatory and antioxidant properties have been described, as well as cytotoxicity and antibacterial actions among others. Clinical studies are lacking.(Li 2021)

Arthritis/Inflammation

Animal data

Flavonoids extracted from the Chinese T. vernicifluum species have been investigated in vitro for anti-inflammatory activity against cyclo-oxygenase and antioxidant action.(Cho 2012, Kim 2015)

Anti-inflammatory activity has been described in rodent studies using homeopathic R. toxicodendron.(dos Santos 2007, Huh 2013, Lee 2016, Patel 2012, Patil 2009, Patil 2011) However, analytical documentation of the content and strength of the preparations used was not included.

Clinical data

A multicenter, randomized but unblinded trial (N = 142) evaluated the homeopathic preparation Disci/Rhus toxicodendron compositum (a composite medication authorized in Germany) in low back pain. The homeopathic injection preparation (51 patients) was not superior to placebo injections (P=0.35).(Pach 2011) A small clinical study (N=30), with some methodological limitations, reported superiority of a homeopathic complex over placebo when combined with physiotherapy for osteoarthritic pain. The homoeopathic complex contained Arnica montana 6CH, Bryonia alba 6CH, Causticum 6CH, Kalmia latifolia 6CH, Rhus toxicodendron 6CH and Calcarea fluorica 6CH.(Morris 2016)

Dosing

Clinical applications are lacking. Poison ivy preparations should not be ingested due to potential for allergy and toxicity.Duke 2002 Desensitization is not generally successful.Gladman 2006

Pregnancy / Lactation

Avoid use. Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions

None well documented. A delayed hypersensitivity reaction (Rhus allergic contact dermatitis) occurred in a patient taking etanercept.Myers 2006

Adverse Reactions

Mild to severe allergic contact dermatitis, typically a pruritic, erythematous, and vesicular rash depending upon point of contact, is well documented. Black-spot poison ivy dermatitis has also been described, with characteristic black lesions.(Lehman 2020, McClanahan 2014, Pittman 2013)

Urushiol is degraded in water and immediate washing of the contact area with a detergent-containing or "grease-cutting" soap is advised.(Gladman 2006) Findings from a randomized clinical study suggest that long courses (15 days, with tapering) of oral corticosteroid treatment are more beneficial than short courses (5 days).(Curtis 2014) Contact dermatitis from homeopathic R. toxicodendron has been reported,(Cardinali 2004) as has dermatitis from ingestion of Rhus lacquer.(Park 2000) The oleoresin urushiol appears to be allergenic only to humans and higher primates. Desensitization is not generally successful.(Gladman 2006)

Toxicology

Dose-dependent genotoxicity has been observed in bone marrow of mice exposed to an extract of T. pubescens (Atlantic poison oak).Mersch-Sundermann 2004

Index Terms

Rhus acutiloba
Rhus toxicarium
Rhus toxicodendron
Toxicodendron quercifolium
Toxicodendron toxicarium

References

Disclaimer

This information relates to an herbal, vitamin, mineral or other dietary supplement. This product has not been reviewed by the FDA to determine whether it is safe or effective and is not subject to the quality standards and safety information collection standards that are applicable to most prescription drugs. This information should not be used to decide whether or not to take this product. This information does not endorse this product as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this product. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this product. This information is not specific medical advice and does not replace information you receive from your health care provider. You should talk with your health care provider for complete information about the risks and benefits of using this product.

This product may adversely interact with certain health and medical conditions, other prescription and over-the-counter drugs, foods, or other dietary supplements. This product may be unsafe when used before surgery or other medical procedures. It is important to fully inform your doctor about the herbal, vitamins, mineral or any other supplements you are taking before any kind of surgery or medical procedure. With the exception of certain products that are generally recognized as safe in normal quantities, including use of folic acid and prenatal vitamins during pregnancy, this product has not been sufficiently studied to determine whether it is safe to use during pregnancy or nursing or by persons younger than 2 years of age.

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